first: If a blocking vampire cannot burn blood to Obtenebration part of the card, will he/she go to torpor?

second: Can the Presence part of the card be used as just as stealth, when bleed is unusable? For actions like equip or hunt for example.

Power of One
[Action Modifier] Action Modifier

[Obtenebration] Obtenebration
[Potence] Potence
[Presence] Presence

[1 Blood]

Requires an anarch.
[obt] Only usable when an action is blocked. The blocking minion burns 2 blood or life (before combat, if any).
[pot] +1 bleed.
[pre] +1 bleed, or +1 bleed and +1 stealth. You cannot play another action modifier to increase this bleed amount.

Post card in question for faster answers.

1. No, burning blood isn't taking damage. So Outside the Hourglass and weather control both do damage before other combat effects and can torp vamps, but this effect is before you enter combat, and just removes blood. A March Halcyon at 1 just becomes empty if she blocked, etc.

2. No. There's only the extra bleed or the extra bleed with stealth.

3. You didn't ask, but potence part is my favorite effect, so I'll say it anyway: pot effect stacks with command of the beast and leverage, so ermangelio anarch can govern bleed with leverage, command, power of one, conditioning for a bleed of 9 for4 cards, 3 blood and the edge

ReverendRevolver wrote: [pre] +1 bleed, or +1 bleed and +1 stealth. You cannot play another action modifier to increase this bleed amount.
2. No. There's only the extra bleed or the extra bleed with stealth.

Indeed. You can't increase the bleed of a non-bleed action. Since the Presence effect gives you +1 bleed in both cases, it doesn't work. It would have worked if it had stated: "+1 bleed, or +1 stealth, or +1 bleed and +1 stealth" (in which case you could have used the second effect to add stealth to a non-bleed action).